Questions in Current Electricity

Select	Question
	Resistance of tungsten wire at $150^\circ C$ is $133\,\Omega $. Its resistance temperature coefficient is $0.0045/^\circ C$. The resistance of this wire at $500^\circ C$ will be
	A metal wire of specific resistance $64\times 10^{-6}ohm-cm$ and length 198 cm has a resistance of 7 ohm, the radius of the wire will be
	A copper wire of length 1 m and radius 1 mm is joined in series with an iron wire of length 2 m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the copper and iron wires is
	For a metallic wire, the ratio $V/i$$(V = $ the applied potential difference, i = current flowing) is
	The resistance of a wire is R. If the length of the wire is doubled by stretching, then the new resistance will be
	Which of the following has a negative temperature coefficient
	The reciprocal of resistance is
	A solenoid is at potential difference 60 V and current flows through it is 15 ampere, then the resistance of coil will be
	All of the following statements are true except
	A potential difference of V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity